A type L meets the Lockable requirements if it meets the BasicLockable requirements and the following expressions are well-formed and have the specified semantics (m denotes a value of type L).
m.try_lock()
Effects: attempts to acquire a lock for the current execution agent without blocking. If an exception is thrown then a lock shall not have been acquired for the current execution agent.
Return type: bool.
Returns: true if the lock was acquired, false otherwise.